320 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



as coelomic or perivisceral corpuscles. The number of 

 these corpuscles in different individuals varies enormously, 

 but two kinds are usually recognisable — amoeboid and 

 spherical. In some individuals the spherical corpuscles 

 are much more numerous than the amoeboid, while in 

 others they are more evenly distributed. It is often rather 

 difficult to decide whether a particular corpuscle is in 

 the amoeboid or spherical condition. It is not really 

 actively amoeboid, yet it is irregular in outline and with 

 no clearly defined contour. It would seem, therefore, 

 that transitional stages may occur at such times when an 

 amoeboid corpuscle, having, as Beddard suggests, 

 become loaded with granules of an excretory nature, 

 ceases to be amoeboid and gradually becomes spherical 

 in outline. Both kinds of corpuscles are granular, the 

 granules sometimes being of a yellowish hue. 



THE ALIMENTARY CANAL. 



The general arrangement of the various regions of 

 the alimentary canal can be clearly seen if the living 

 worm be examined under the microscope, owing to the 

 transparency of the body wall. If examined in this way, 

 it will be seen that the wall of the alimentary canal in 

 the first five segments is almost colourless, or only 

 slightly yellowish in colour. In segment 6, however, the 

 appearance changes very suddenly, for the wall has now 

 a blackish or brownish hue, due to the presence of 

 specialised cells of a glandular nature known as chlora- 

 gogen cells, which will be described in detail later. More 

 posteriorly the colour again changes, becoming gradually 

 lighter and lighter until in the region of the anus the 

 wall of the alimentary canal has again a pale yellow 

 colour. As in all Oligochaeta, the alimentary canal has 



